Poikilothermic organisms, e.g., marine bivalves, tend to undergo reduced metabolism akin to hibernation at temperatures below 5° C. They can remain in this state using their own stored glycogen as a source of energy for anaerobic metabolism for long periods of time while suffering very low levels of mortality.
However acclimating to the declining environmental temperature is physiologically very stressful, and as a result, poikilothermic organisms such as marine bivalves, can suffer an undesirable level of mortality in a decreasing temperature environment such as the transition from the fall season to the winter season in the northern hemisphere. Certain bi-valves such as hard clams and oysters are of high market value, and excessive mortality in stocks of such bi-valves can have significant negative economic impact.
While not wishing to be bound by theory, it is presumed that in the non-limiting ease of marine bi-valves, as temperature decreases the cell-membranes of a bivalve experience changes in fluidity due to the phase transition of phospholipids which are present in the cell membranes of the bivalve. While this and various other factors can play a role in cell membrane fluidity in marine bi-valves, to more or less of an extent, these changes in fluidity of the cell membranes of the bivalve can result in increased stress levels to the bi-valve and increase the level of mortality in stocks of bivalves.